If anyone cares, I also wrote a generalized trinket tracker last year that does the following.

For each trinket slot-

If it's an activated trinket, it shows the activation cooldown;

If it's an ICD trinket, it shows the internal cooldown;

If it's an RPPM trinket, it shows the expected (average) time until next proc.

As a caveat, the RPPM display is probably a bit less useful than you are thinking right now. An RPPM proc is still very random; the only reason the "expected time until next proc" is nonconstant in the first place is Blizzard's bad luck streak prevention mechanic. That said, it can still be mildly useful as long as you recognize that it's only meaningfully tracking the bad luck streak prevention. I'd also note that it's not useful for predicting procs at the start of a boss fight since Blizzard now resets the bad luck streak timer at boss encounter start.

Trinket data for ICD or RPPM trinkets has to be entered manually (although I wonder if I can parse that from Blizzard's tooltips now), but it's all stored in a fairly obvious format in the TrinketData custom trigger. This is the data that's implemented currently: